Work

Evidence of multiscale supercurrents in K-doped BaFe2As2

Year: 2025

Type: article

Abstract: K-doped BaAs2Fe2 (K-Ba122) superconductor is a promising material for applications. However, it has been found challenging to achieve high critical current density (Jc ) in untextured bulk sample. In this paper we investigated bulk samples prepared by varying the milling energy density, which affects the grain and grain boundary microstructures, and we investigated their magnetic performance to better understand what causes their different Jc . We found that in our samples, which all have small grain size, Tc does not appear directly correlated to Jc . Moreover, AC susceptibility reveals in at least one case obvious signs of multiscale supercurrents, not caused by granularity but that directly influence the overall Jc performance. Considering the microstructural features and the magnetization response we ascribed the Jc differences to lack of connectivity on a larger scale due to nano-cracks at some grain boundaries, which subdivided the samples into macroscopic regions and inevitably limited the overall performance. We discuss possible routes to overcome those extrinsic current-blocking defects.

Source: Superconductor Science and Technology

DOI: 10.1088/1361-6668/adc633

Authors: Chiara Tarantini, Shah Alam Limon, Keyou Mao, Eric E Hellstrom, Fumitake Kametani

Institutions: Florida State University, National High Magnetic Field Laboratory, Florida A&M University - Florida State University College of Engineering

Language: English

Topic: Iron-based superconductors research

Subfield: Electronic, Optical and Magnetic Materials

Field: Materials Science

Domain: Physical Sciences

Open Access status: hybrid

Estimated APC paid: $3,325

Funders: U.S. Department of Energy, Division of Materials Research, State of Florida